Fluid projection apparatus



1 y 1962 D. A. YOUNG 3,033,426

FLUID PROJECTION APPARATUS Filed Jan. 12, 1959 INVENTOR. DAVID A. YOUNGATTORNEY United States Patent Ofiice 3,633,426 FLUKE) l RGJECTIQNAPPARATUS David A. Young, Washington, D.C., assignor to Aeroget- GeneralCorporation, Azusa, Calif., a corporation of Ohio Filed Jan. 12, 1959,Ser. No. 786,345 7 Claims. (Cl. 222-3865) 'The present invention relatesto fluid projection apparatus and particularly to such apparatus adaptedfor use in flame throwers, fire extinguishing apparatus, pressurizationdevices and the like.

An object of the present invention is to provide a novel method of andan improved means for the projection of fluids.

Another object is to provide an improved fluid projection apparatus ofthe free piston type.

Still another object is to provide improved fluid projection apparatusof the piston type wherein the fluidpropelling piston may follow aconvoluted or non-linear ath.

P In its preferred embodiment, the invention comprises a portable fluidprojection apparatus such as a portable flame thrower incorporating afuel tank of convoluted form and circular cross section. Gas underpressure is admitted to the tank on one side of a piston therein. Fuelin the tank on the opposite side of the piston is ejected therefrom bythe admitted gas pressure driving the piston through the length of thetank. A fuel ejection nozzle is mounted at the exit end of the tank foretficient discharge and direction of the fuel.

A principal feature of the present invention is the use of a piston notconnected to any other portion of the apparatus and hereinafterdesignated as a free piston. The piston of the present invention is alsocharacterized by having a periphery effective to seal against the wallsof a tubular tank, whether of straight, curved or folded configuration,thereby keeping separate the fluids contained in the tank on oppositesides of the free piston, regardless of the pressure acting on thefluids.

These and other objects and features of the invention will hereinafterappear from the following specification read with reference to theaccompanying drawings where- FIG. 1 is a longitudinal section of apreferred embodiment of the present invention utilizing a free piston inthe form of a ball;

FIG. 2 is a cross sectional view on the plane 2-2 of FIG. 1;

FIG. 3 is a longitudinal section through a second form of free piston;

FIG, 4 is a view taken on the plane 4-4 of FIG. 3;

FIG. 5 is a longitudinal section through a third form of free piston;

FIG. 6 is a view taken on the plane 6--6 of FIG. 5;

FIG. 7 is a longitudinal section of a fourth form of free piston; and,

FIG. 8 is a view taken on the plane 88 of FIG. 7.

Referring nowto FIG. 1, the device is shown as having a U-shaped tank 10of uniform circular cross section. A gas generating chamber 11 having aremovable head closure 11b is mounted on one removable end 11a of thetank and a detachable nozzle mounting member 12 is mounted on the otherend, the nozzle 12b being closed by any suitable closure 12a until thedevice is put into use.

A gas chamber 11 is shown as one way of supplying pressure fluid to thetank but it is immaterial to the invention how pressure is supplied. Forexample, a container storing gas or hydraulic fluid under pressure mightbe connected to the inlet end of the tank and controlled by a valve ofany suitable type.

A gas generating chamber 11, which is provided with a removable headclosure 11b, contains a grain or charge 13 of slow burning propellant. Afree piston 14 is positioned initially adjacent the gas inlet 15 fromthe chamber 11 when the grain 13 is ignited by any suitable means suchas a squib and electrical connector indicated at 11c.

Free piston 14 may be formed from a suitable elastomer as a solid ballas shown, or as a hollow ball, and the surface of the ball 14 ispreferably sufliciently resilient to insure that effective sealing isprovided notwithstanding minor imperfections of the inner surface of thetank 10. A suitable material for the piston is an elastomer such as asynthetic rubber of 20-40 Shore hardness and resistant to heat and tothe action of various corrosive fluids or fuels acting to soften ordissolve natural rubber.

The space in the tank between the free ball piston 14 and the nozzlemounting member 12 is filled with the fluid 16 to be expelled. v

When the grain 13 is ignited, gas under pressure enters the tank 10 andforces the ball piston 14 toward the nozzle 12b until all the fluid hasbeen expelled, the force exerted by the fluid initially rupturing orblowing off closure 12a.

The cross-sectional area of the tank 10 is slightly widened at itsterminus in the nozzle mounting member 12 so that the seal between thepiston 14 and the walls of the tank 10 is broken when the flexiblepiston 14 reaches this point. This permits the pressurizing gases orfluids to completely exhaust all of the material being pumped.

When the device is employed as a flame thrower suitable ignition means(not shown) are arranged to ignite the ejected fluid to form a burningstream. Such means are well known in the art. See, for example,assignees copending U.S. patent application No. 786,348, filed January12, 1959.

When the ball piston 14 is nested in the enlarged portion 12c of thedetachable nozzle mounting member 12, the latter can be demounted andthe ball piston 14 removed, the nozzle member 12 replaced, and a freshclosure 12a put in position.

After removal of end 11a of the tank 10, it can be re charged with fluid16, the ball piston 4 placed in the tank 10, the tank end 11a replaced,and a fresh grain of slow burning propellant 13 is positioned in chamber11, after which the device is ready for reuse. The form of the freepiston shown in FIGS. 3 and 4 differs from that previously describedwith reference'to FIG. 1 in that the free piston is formed or molded asa hollow ovel body 17 having an open end 18 facing toward the gasopening 15 when positioned in the tank 10. Reinforcing or stiffeningmeans 19, which may be formed as a thick walled tube of syntheticrubber, is arranged around the maximum inner diameter of membgr 17 andcemented in place with a suitable adhesive 2 l The free piston shown inFIGS. 5 and 6 comprises a hollow body open at one end so that gas orfluid may enter the body thereof.

The free piston 21 shown in FIG. 5 comprises a cuplike outer body ofmolded synthetic rubber having a molded lip 22 formed to provide aninwardly projecting flange 23. An extension type resilient membercomprising a plurality of curved metal strips 24 extend from a centercupped disc 25 secured to the forward wall 26 of the piston 21 by amember 27 extending forwardly. Member 27 is intended to aid removal ofthe free piston 21 from the tank 10 by pulling on the exposed forwardend of the member 27, or to aid insertion into the tank 10 by pushing onthe rearward end of the member.

The rearward ends of the fingers 24 tend to maintain Patented May 8,1962 It the piston 21 in normally extended position. The side walls 28of the free piston 21 are shaped to afford a certain amount ofpliability in passing around small radius curves in the tank yet will beerected to normal form after passing through such curved portions.

The form of the free piston 29 shown in FIGS. 7 and 8 is a variation ofthe form of free piston 17 shown in FIGS. 3 and 4. The free piston 29 iscup-shaped with its open side positioned toward the gas entry 15. Thewall 29:: is positively kept in open position by a plurality of flatspring fingers 30 struck from a sheet to leave a central disc 30::secured to the center of the cup by a rivet 31. It will be evident thatthe rivet 31 may be substituted by a securing member formed similarly tothe member 27 shown in FIG. 5.

This piston cup wall 290: may be molded from a suitable elastomer suchas a synthetic rubber, with an inturned rim 32 covering the ends of thespring fingers 30.

In operation of the various forms of the invention, the wall of the ballpiston 14 slides along the inner surface of the tank 10, the surfacessliding at different rates round the smaller diameter curved surface andthe opposite larger diameter curved surface at bends in the tank withoutlosing efiective sealing contact therewith. The various forms of thefree piston shown, and others which may be devised, operate in themanner described and are elfective to separate fluids on opposite sidesof the piston while transmitting pressure from one side to the other ofthe free piston.

Several preferred embodiments of the invention have been specificallydescribed and shown by way of example only and not as limitative of theinvention since changes may be made therein by those skilled in the artwithout departing from the scope of the invention as defined by theclaims appended hereto.

I claim:

1. Fluid projection apparatus comprising: an elongated tubular tank ofconstant area of cross section and having a longitudinal axis arcuatelyformed in part, said tank adapted to contain fluid to be expelledtherefrom by pressure fluid admitted thereto; an inlet to and an outletfrom said tank; and a free piston shaped to provide a peripheral surfacein sealing engagement with the inner surface of the tank throughout thetravel of the free piston through the tank under the force exerted onsaid piston by pressure fluid admitted to said tank to expel fluid insaid tank between said piston and the outlet from said tank.

2. Fluid projection apparatus comprising: an elongated tubular tank ofconstant area or circular cross section and having a longitudinal axisarcuately formed in part, said tank adapted to contain fluid to beexpelled therefrom by pressure fluid admitted thereto; an inlet to andan outlet from said tank; and a spherical free piston having a diametersuch that a peripheral portion of its surface remains in sealingengagement with the inner surface of the wall of the tank throughout thetravel of the free piston through the interior of the tank.

3. Fluid projection apparatus as set forth in claim 2 and in which saidspherical piston is made of an elastomer having a hardness of from about20 to about 40 Shore and resistant to deterioration by the fluidscontained in the tank.

4. Fluid projection apparatus comprising: an elongated tubular tank ofconstant area of cross section and having a longitudinal axis arcuatelyformed in part, said tank adapted to contain fluid to be expelledtherefrom by pressure fluid admitted thereto; an inlet to and an outletfrom said tank; and a free piston having a hollow body of greater lengththan width, closed at one end, and open at the opposite end, and ofcircular cross section at all sections taken normal to its longitudinalaxis. said open end being faced toward the inlet of the tank throughwhich fluid pressure is supplied to the tank, the diameter of said bodyincreasing from that of its open end to a maximum at a pointintermediate its ends and thereafter decreasing to a minimum diameter atthe end opposite its open end, said piston having a maintained shapewhile propelled by said pressure fluid and having sealing engagementwith the inner surface of the said tank throughout the piston travel.

5. Fluid projection apparatus as set forth in claim 4 and in which saidfree piston comprises resilient means positioned within the piston andengaging the inner surface of the wall thereof to effect stiffeningthereof.

6. Fluid projection apparatus comprising: an elongated tank of constantcross section having a longitudinal axis arcuately formed in part, saidtank having an inlet and an outlet, said tank being adapted to containfluid to be expelled from its outlet by pressure fluid admitted to itsinlet and a free piston arranged within said tank, said pistoncomprising a cup-like body of moldable material, and resilient meanswithin said body effective to maintain the normal form of the body whilemoving in certain portions of the tank in response to pressure fluidactuation and also permitting said piston to pass through other portionsof the tank having a nonlinear longitudinal axis, in sealing engagementwith the inner surface of the tank throughout the piston travel.

7. Fluid projection apparatus comprising: an elongated tank of constantarea of cross section and longitudinal axis arcuately formed in part,said tank adapted to contain fluid to be expelled therefrom by pressurefluid admitted thereto; an inlet to and an outlet from said tank; a freepiston having a cup-like body of flexible resilient material placed insaid tank with its open end facing the inlet to the tank through whichfluid pressure is introduced into the tank; and flat resilient stripssecured to the closed end of and within the cup-like body to resilientlymaintain the cup-like contour of said body while positioned in andmoving through the tank, under the force of said fluid pressure to expelfluid through the tank outlet.

References Cited in the file of this patent UNITED STATES PATENTS708,448 Wyman Sept. 2, 1902 1,320,858 Hitch Nov. 4, 1919 1,699,494Schmidt Jan. 15, 1929 2,361,647 Nyden Oct. 31, 1944 2,872,083 Murphy etal. Feb. 3, 1959 2,880,913 Peyron Apr. 7, 1959 FOREIGN PATENTS 3,610Great Britain Feb. 10, 1897 202,156 Great Britain Aug. 16, 1923 791,113France Sept. 23, 1935

